Pulp-screen and process.



D. L. BELLINGER,

PULP SCR-EEN AND PROCESS.

APPLICATION FILED ocT.25. 1915.

2 SHEETS-SHEET I.

Patented; Nov. 28, 1916.

LQAUL imm@ NTURIl/EV D. L. BELLINGER. PULP SCREEN AND PROCESS. APPILICATION FILED ocT.25. 1915.

Patented Nov. 28, 1916.

LQUUL 2 SHEETS-SHEET 2.

' tailings, whichl cannot the invention to the inner surface thereof. The

.outward -along the -inner irren amarre pagina* oriana.,

DANIEL L. BELLINGER, OF GLENS FALLS, NEW YORK.

PULP-SCREEN AND PROCESS.

i,acaaci.

Specication of Letters Patent.

llpatentedhov. 2d, im@

Application iled October 2li, 1915. Serial No. 57,763.

y To all whom t may concern Be it known that I, DANIEL L. BELLINGER, a citizen of the United States, residing at Glens Falls, county of lVarren, and State of N ew York, have invented certain new and useful Improvements in Pulp-Screens and Processes; and I do hereby declare the following to be a full, clear, and lexact description vof. the invention, such as will enable others skilledl in the art to which it lprises an open-ended rotary screen and means for delivering the unscreened pulp accepted stock containing the fine fibers, or practically all of them, will pass screen and into a suitable receptacle. rllhe pass through .the screen, form into a roll which works its Way surface of `the lower portion of thev screen and 'is progressively and continuously discharged at thel open end of the screen into a suitable receiving device. Machines constructed in accordance with possess many advantages'in trough or other the art, vprominent lamong which are the following i should such a rupture-or rl`hey are self cleaning, and are free from accumulations of slime, and'v may therefore vbe operated fora period of several days with practically no4v attention. They are economical in operation, requiring but a small amount of power per ton capacity, and the. cost of negligible, as the screens are not subjected to sudden and violent strains, tending tov rupturethem, as is theA case Vwith certain types of rotary screens now in use. Accordingly, the possibility of .any part offthe tailings passing into the receptacle which receives the screened. pulp (which would occur breaktake place) is wholly avoided. The loss of paper stock in the screening operation is reducedto -a minimum, as th'e pacity.

through lthe '11,` with. which the maintenance is practically a rotary screen form, and preferably composed of perfotailings carry olf but a small percentage'of the fine fibers originally present in the unscreened pulp andthe improved screens effect a considerable reduction of the mill space required for creens of a given ca- Referring to the drawings, illustrating one embodiment of the invention; Figure l is a cross section of a screen battery showing one screen of a pair' in elevation andthe other in section, and Fig. 2 is a side elevation of a battery consisting of a plurality of screening machines arranged to be driven from a single source of power. In this view, parts are broken away for the sake of clearnessand the rotary screen of one of themachines is shown in section. I.

Referring to the drawings, there is shown a battery consisting of a plurality ofpulp v screening machines arranged in pairs and driven from a single source of power. It is to lbe understood, however, that the inven? tion is not limited to this particular'arrangement of machines, but that it includes i generically the construction of a single machine whether the machine lbe operated individually or in unison with other machines.

The rotary screens 3 of each pair of machines, hereinafter described, are mounteduponthe ends of a common shaft 4f, journaled in bearings 5,'mounte'd in spaced relation on a concrete pedestal structure 6 leX- tending lengthwise of the batter-y. Secured to the shafts between ,the screens are pulleys 7 which are driven 'by a belt 8 one lap 'ofwhich engages alternately thelower and peripheries of the pulupper portions of the leys, as -clearly shown in Fig. 2.. The belt 8 is driven from a pulley 9, secured to the shaft l0, to which is also secured a' pulley'A engages. c

Each screening machine is provided with rated ysheet metal. The perforations 13,

which in the embodiment ,of the invention shown, are arranged in the usual staggered relation to` one another, are of such size as will permit-the fine fibers of thepulp -to 3, preferably cylindrical in m0 ego p 95, main -drivingfbelt vl2 i pass freelyftherethrough butV will prevent`V the passage of the tailings.

lln practice, l have foundvthat for; the

screeningof ground wood, for use in the manufacture of newspaper, wall paper,and

vidual screens.

half tone paper, it will be appropriate and desirable to Ause copper screen plates .05 inches in thickness, and having circular perforations .085 inches in diameter and spaced uniformly at distances of g of an inch from center to center. I do not limit myself to the use of plates of this gage and this size and distribution of perforations, inasmuch as varying conditions may call for more or less modification thereof to produce the best results. In general, however, they will be found highly efficient, particularly in the screening of the usual qualities of ground spruce and similar stock.

At one of its ends, the screen is provided with a head 14 for closing at that'end, and this head is provided with a hollow hub for securing it to the shaft 4 by which it is rotated. The opposite end of the screen terminates in an annular imperforate band 15, and the inner surface of the screen is unobstructed at the open end thereof to perF mit the free discharge of the tailings therefrom in the manner hereinafter set forth.

Adjacent the open end of the screen is a pulpsupply conduit or trunk 16 into which the stock is pumped continuously and fr'om which it is supplied through control valves 17 to the distributer boxes 18 of the indibox at the central lower portion, as shown in Fig. 1, and the end Walls of the box flare upwardly to produce an even low velocityA of overflow at the upper side edges of the box.

Extending downwardly from the upper edges of the side walls of the feed box are distributing inclines 20, which are inclined outwardly with respect to the feed box, and having their lower edges in close proximity to the inner surface of the screen to direct the pulp against the screen surface with the. necessary velocity of impact as it leaves the discharge end of the inclines. Suitable walls 21 are provided at the ends of the distributers, in order to conine'the flow of the pulp in an even sheet of the width of the distributing inclines. It will be understood, of course, that good results can be obtained if but one distributing incline is used, but it is preferred to use two arranged to deliver pulp simultaneously to opposite sides of the screen, as the capacity of the machine is thereby increased.

The distributing inclines 20 extend axially of the screen from the head 14 to a line, as indicated in F ig. 1, which is somewhat short of the line of attachment of the annular band 15 at the open end of thewscreen. The object of this arrangement is to effect a progressive drying of the tailings as they work their way toward the open end of the screen in the manner hereinafter described. The purpose of the annular imperforate band or apron 15 is to prevent the under- The pulp enters the feed flow) of tailings around and under the edge of, the screen at its open end and into the accepted stock reservoir or conduit.

In the concrete foundation below the screen is a receptacle or conduit which receives the accepted stock and from which the stock may be conducted to any suitable point of delivery, as, for instame, the stock chest. Adjacent the open end of the screen and below the same is a trough Q1 into which the tailings are discharged. The bottom of the trough is preferably inclined to facilitate the flow of the tailings into any suitable receptacle, from which they may be forwarded or removed as desired. lhen a plurality of the machines are arranged in battery formation, the receptacle 22 and trough 21 are preferably so formed as to be common to the screens of those machines which are in line with one another.

In operation, the raw stock is.supplicd continuously from the .supply conduit 16 to the feed box 18, under a suitable lowl` pressure head, the rate of How being controlled by the gate 17. The head is preferably just about suflicient to raise the level of the stock in the feed box slightly above the verges thereof so that thestock overflows both verges of the feed box and runs downwardly over the distributors Q0 and is delivered with the impetus due to its drop, against the as- .cending and descending portions of the inner surface of the screen.

A substantial proportion of the line fibers, say about eighty per cent. (80%) of the accepted stock fibers, together with a greater part of the water diluting the raw stock, will pass through the perforations in the screen, and into the receptacle or conduit The remainder, about twenty per cent. (20%) of the accepted stock fibers will seep through the tailings and the screen perforations, between the end line of the distributer iuclines and the line of attaclnnent of the annular band 15, during the progressive drying of the tailings as they move toward the discharge end of the screen.

Below the distributer which delivers to the descending portion of the screen surface, the tailings tend to assume a sheet formation.. After passing the lowest point of rotation of the screen, but before reaching the point at which the pulp is delivered to the ascending portion of the surface of the screen, this sheet of tailings detaches itself progressively from the inner surface of the screen and progressively rolls back upon itself. T he tailings which are contained in the pulp delivered to the ascending portion of the screen surface form small irregular masses which tend to rise but which quickly detach themselves and drop back to add to the roll formation; or, if the distributer delivering to the ascending' portion of the screen is alone used, the detached irregular masses referred to assemble themselves to form the roll.

When the internal diameter of the screen is about forty inches, a suitable speed of rotation will be about 25 revolutions per min ute, more or less, and, as the rotation of the screen continues, the roll of tailings, which is continuously forming, progressively'Works its way out of the open end of the screen, longitudinally, at the lower portion thereof. The forming roll of tailings occupies normally a position somewhat higher on the average than half way between the lower'-` most point of the screen and its horizontal central plane, on the ascending side of the screen, and occupies this position whether one or both distributers are in use. Trailing behind the forming roll is the sheet formation referred te, which becomes more and more definite and dense as it approaches the region of the roll and finally merges therewith.

l regard as one of the particular merits of the invention the fact, as established by its use in practice under standard mill conditions, that, in spite of the normal tendency for the tailing slivers to wedge in the screen perforations, no clogging takes place, a circumstance attributable largelyto the influence of the forming roll of tailings, which. as it rolls back upon itself, serves to withdraw from the perforations any portion of the slivers which may have temporarily lodged therein.

l41 or the purpose of preventing the accumulation, on the inlet pipe between the valve 17 and the feed box, of detached irregular masses of tailings carried up by and dropped from the screen land the band l5, I provide the inclined plate or chute 19 positioned at the end of the distributer inclines and adapted to catch such massesand return them into the axially progressing roll or mass of tailings.

lllhat l claim is:

l. The method of screeningr paper pulp stock which consists in discharging the stock against the inner surface of a rotating cylindrical open-ended perforated screen in a direction substantially transverse to the aXis of the screen and at a level substantially above the lowest point of travel of the screen, the speed of rotation of the screen being so calibrated to the stock treated and the level of the feed that the tailings will fall away from the surface of the screen before the level of the feed is reached, continuously and progressivelyA forming` a roll along the ascending lower portion of the screen and will continuously and progressively move out of the open end of the screen in a longitudinal direction. l

2. rlhe method of screening paper pulp stoclr which consists in discharging the stock upon a clean portion of the inner surface f a rotating cylindrical perforated screen in a lateral direction and 1n a sheet extending lengthwise of the screen, and keeping the screen perforations at the levelof discharge clean by rotating the screen under such conditions that the tailings separated by the screen will continuously and progressively roll back along the ascending lower portion of thel screen forming a Aroll which withdraws from the perforations any slivers that have temporarily lodged therein.

In a paper pulp screening machine, av rotary cylindrical screen having a freely open end constituting the discharge verge for the tailings of the screening operation, a distributer extending lengthwise of the screen for discharging the pulp in a lateral direction upon the inner surface of the screen., and means adjacent' the open outlet end of the screen for receiving the tailings as they continuously and progressively move out over the open tailings-discharge verge of the screen; substantially as described.

.In a paper pulp screening machine, a rotary cylindrical screen, having a freely open end constituting the discharge verge for the tailings of the screening operation, a distributer extending lengthwise of the screen for discharging the pulp upon the inner surface of the screen in opposite lateral directions, and means adjacent the open outlet end of the screen for receiving the tailings as they continuously and progressively move out over the open tailings-discharge verge of the screen; substantially as described.

5. In a paper pulp screening machine, a rotary cylindrical screen having a freely open end constituting the discharge verge for the tailings of the screening operation, a distributer extending lengthwise of the screen for discharging the pulp in the form of al sheet and in a lateral direction upon the inner surface of the screen, the distributer lterminating short of the discharge end of the perforated portion of the screen to afford a screening region for the progressive drying of the tailings, and means adjacent the' open outlet end of the screen for receiving the tailings asthey continuously and progressively move out over the open tailings-discharge end of the screen; substantially as described.'

lin a paper pulp screening machine, a rotary cylindrical .screen having a freely screening region for the progressive drying lllltl Milt I j of the tailings,

screen for receiving the tailings as they continuously and progressively move out over the open tailings-discharge end of the screen; substantially as described.

7 In a paper pulp screeningY machine, a

rotary cylindrical screen having a freely open end constituting the discharge verge portion thereof vuter for discharging for the tailings of the screening operation, an annular imperforate band attached to the discharge endof the screen to prevent the underflow of the tailings, a distributer eX- tending lengthwise of the majorportion of the perforated part of the screen and arranged to discharge the pulp in a horizontal sheet against the inner face of the side walls of the screen at aboutthe level of the axis of rotation, end of the screen for receiving the tailings as they continuously and progressively move out over the open tailings-discharge end of the screen; substantially as described.

8. In a paper pulp screening machine, a rotary cylindrical screen, having a distributer for discharging the pulp upon the inner surface of the screen along the descending portion and also along the ascending-portion thereof; substantially as described. g

9. vIn a paper pulp screening machine, a rotary cylindrical screen,having a ing portion and also alongl the ascending central horizontal plane of the screen; substantially as described; i y

10. In a paper pulp screeningmachine, a rotary cylindrical screen having a distributer consisting of an inclined flow plate eX- tending longitudinally of thescreen for diand means adjacent theopen outlet l distribthe pulp upon the in- Vner surface of the screen along the descend-l andv at approximately thev scribed.

11. In a paper pulp screening machine, a A

double series of rotary cylindrical screens open at one end and closed at the other, distributers for discharging the pulp upon the inner surfaces of the screens, rotary shafts common to the two series and each carrying two `ofthe screens, and drive pulleys upon the several shafts intermediate of the screens thereon; substantially as described.

12. In a paper pulp screening machine, a double series of rotary cylindrical screens open at one end and closed at the other, distributers for discharging the pulp upon the inner surfaces of the screens, rota'ry shafts common to the two Series and each carrying two of the screens, and drive pulleys upon the several shafts intermediate of the screens thereon, the said pulleys being provided with a common drive belt extending under and over alternate pulleys of the series; substantially as described.

13. In a paper pulp screening machine, a rotary cylindrical screen having a freely open end constituting the discharge verge for the tailings of the screening operation, a feed box and distributer within the screen, a feed pipe projecting into the screen and lead ing to the feed box, and a deflecting plate supported above the feed pipe to catch and return to the bottom of the screen any tailings that may be carried up and dropped abovel the feed pipe; substantially as de- In testimony whereof I aiix my signature.

' v DANIEL L. BELLINGER. 

